The present invention relates to an unsaturated polyester resin composition useful as general paints, and more particularly to an unsaturated polyester resin coating composition useful as putty for repairing of cars, and as sealing material for joint sections of buildings, sashes or insertion section of glass, as well as paints.
An unsaturated polyester resin prepared by reacting an unsaturated polybasic acid, a saturated polybasic acid and a polyhydric alcohol has been widely employed as paints, adhesives, moldings, and the like. However, practically, only these polybasic acids and polyhydric alcohol has scarcely been used in producing of the unsaturated polyester resin. That is, modifying components such as cyclopentadienes or dicyclopentadienes are introduced into the above unsaturated polyester resin for improving the shrinkage property or water-resistance, or a polyhydric alcohol allyl ether is introduced into the unsaturated polyester resin for giving the air drying property to the unsaturated polyester resin.
Paints prepared from such a polyester resin have some advantages such as excellent gloss and beautiful finishing. However, the paints are required to have higher functions, because the paints are generally employed out of doors.
The above unsaturated polyester resin has been known as materials for general paints, but a satisfactory unsaturated polyester resin suitable for putty use which particularly requires strict properties, has not been prepared. That is to say, a composition prepared by admixing a filler and a vinyl monomer with the abovementioned unsaturated polyester resin, particularly the unsaturated polyester resin to which a polyhydric alcohol allyl ether component is introduced, has hitherto been employed as putty, and proper contrivances such as controling of a mixing ratio of the components have been made in order to employ the unsaturated polyester resin as putty. However, there is room for improvement, because the unsaturated polyester resin employed for general paints is only used for putty. That is to say, the above unsaturated polyester resin has the following problems to be solved.
(1) It is necessary to increase an adhesion property, particularly an adhesion property in the wet state (hereinafter referred to as "wet adhesive strength") of unsaturated polyester resin, to substrates, particularly to metals.
(2) It is necessary to give an extremely quick drying property to the unsaturated polyester resin.
(3) In case of a putty used for repairing cars, it is further required to increase the adhesion property to top coats in addition to the requirements (1) and (2). It is also necessary that the good gloss and sharpness of the coating surface are maintained for a long term, even if the coatings are exposed to severe conditions of temperature and humidity of the open air, and that the coatings have such heat-resistance that even if the coatiangs are exposed to high temperature, for instance, around an engine, the surface properties of the coatings are not lowered.
An object of the present invention is to provide an unsaturated polyester resin coating composition which can solve the above problems.
This and other objects of the present invention will become apparent from the description hereinafter.